1. Field of the Invention
The present invention relates to an information storage device which stores management data, such as that for content data, in a semiconductor memory and a stored data processing method which manages stored data preserved in the semiconductor memory.
2. Description of the Related Art
An information storage device which uses a semiconductor memory as a recording medium is coming into wide use in recording and reproduction of information, such as content data, because it allows multi-channel simultaneous multi-access and high-speed random access. In particular, the information storage device contains no moving parts and therefore has the advantage of being high in reliability.
However, the number of times the information storage device may write data to the semiconductor memory is small as compared with a hard disk drive (HDD). Therefore, repeating the writing of content data to and deleting of it from the semiconductor memory over a long period may cause a memory failure. Such a failure is the main obstacle to data being reliably stored in the semiconductor memory.
In particular, with a conventional semiconductor memory storage device using a NOR flash memory, at the time of writing of moving images, management data produced with each frame of the moving images are stored in a specific area of the memory. Repeating the writing and erasing of moving images involves a large number of operations of writing management data to and deleting it from the specific area of the memory, which may result in the occurrence of a memory failure and cause or threaten loss of information in the memory.
There is a technique which permits the number of times information can be stored in a semiconductor memory to be virtually increased by providing the semiconductor memory with a plurality of storage areas, counting the number of times information is stored in the memory, and changing the storage areas in sequence according to the information storage count (see, for example, JP-A No. 11-144478 [KOKAI]).